Balanced chamber-clearance unloader



' mawsfi w. PRELLWITZ BALANCED CHAMBER CLEARANCE UNLOADER 2 sheets-sh Filed Aug. 4, 1926 INVENTOR. W223 a m Pare wz BY 1 J I HIS A TTONEYS.

Feb. 8, 1927.. 1516,98

W. PRELLWITZ BALANCED CHAMBER CLEARANCE UNLOADER Filed Aug. 4. 1926 2 Sheets-Sheet 2 Patented Feb. 8, 1927.

UNITED STATES PATENT OFFICE.

WILLIAM PRELLWITZ, EASTON, PENNSYLVANIA, ASSIGNOB TO INGERSOLL-RAND- COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

BALANCED CHAMBERCLEARANCE UNLOADER.

Application filed August 4, 1926. Serial No. 127,058.

This invention relates to compressor 1111-- loaders, but more particularly to a step by step 'unloader using both clearance chambers and inlet valve openers. The objects of the invention are to obtain a balanced chamber clearance unloader in conjunction with a free air unloading system, in which inlet valves are held open by valve openers.

The invention is shown in several of its preferred forms in the accompanying drawings, in which Figure 1 is a diagrammatic representation partly in sectional elevation showing a single cylinder, and 1 Figure 2 is a similar view showing the invention applied to a compound compressor. Referring to the drawings, and at first more particularly to Figure 1, the cylinder A having the piston B receives air from the intake C and discharges it from the discharge outlet D to the receiver E. The compressor is provided with the usual inlet and discharge valve F and G which may be plate valves and two of the inlet valves H and J at each end of the cylinder are provided with valve openers of any suitable type. In this instance, the valve 1 stems are provided with the pistons K operating in the cylinders L and fingers O are adapted to open the valves when fluid pressure is supplied behind the pistons through the pipes 3 and 4. Springs P normally retract the fingers.

Clearance chambers Q, and R having clearance valves S and T are provided for each end of the'cylinder and each valve has valve opening mechanism comprising the pistons U operating in the cylinders V. The springs W normally keep the valves closed and they 40 are opened by fluid pressure supplied through the pipes 1 and 2, preferably receiver pressure. The clearance chambers and clearance valves are separate and distinct from the compressor Valves and are independent of said compressor valves.

' A suitable regulator automatically controls the clearance valves and inlet valve openers and this regulator may be of any suitable type. A simple regulator is shown comprising the cylinder X and piston Y, one end of the piston being subject to receiver pressure throughthe pipe (I. An adjustable retracting spring I) returns the piston and the cylinder is provided with the vent c. The pipesl, 2, 3 and 4: lead respectively to the ports d, e, f and g and the piston Y: is cut away at the portion h so that as the piston moves to the left as Figure 1 is viewed, step by step, the ports d, e, f and g are successively opened to receiver pressure. In the operation of the apparatus, the clearance valve S is first opened to unload the compressor one-quarter, then the clearance valve T is opened to unload the compressor one-half and produce a balanced condition. Next the inlet valve H is held open to unload the compressor three-quarters, and finally the inlet valve J is held open to produce no load.

In Figure 2 showing the compound compressor, the low pressure cylinder j and high pressure cylinder 70 are each provided with the same system of unloading as illustrated in Figure 1, that is, each cylinder has two clearance chambers Q and R and the inlet valves H and J provided with valve openers. The low pressure cylinder discharges into the intercooler 0 through the pipe ;0 and the pipe 9 connects with the intake 7' ot the high pressure cylinder which discharges through the pipe d to the receiver E.

The connections through the pipes 1, 2, 3 and 4 are connected in pairs to the ports d, and g of the regulator so that in the series of steps of unloading, opposite ends '85 of the low and high pressure cylinders are simultaneously unloaded.

In the operation of the apparatus, first, the two clearance valves S at opposite ends of the, two cylinders are opened to unload the compressor one-quarter, then the two clearance valves T at opposite ends of the cylinder are opened to produce halt load. Next, the inlet valves H are opened. and finally the inlet valves J are opened. These 9 steps are all accomplished successively as the lston Y moves to the right in the cylinder as Figure 2 is viewed and the steps are repeated in reverse order to unload the compressor.

I claim: In a compressor unloader, the combination 6 of a cylinder and piston, inlet and discharge valves, a receiver, a clearance chamber and clearance valve for each end of the cylinder, both independent of the compressor valves, a valve opener for an inlet valve at each end of the cylinder, and an automatic regulator 10 responsive to receiver pressure for opening first one clearance valve, then the other, and then opening the said inlet valves one after the other, for step by step unloading.

In testimony whereof I have signed this 15 specification.

WILLIAM PRELLWITZ. 

